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Secci ME, Kelley LK, Avegno EM, Holmgren EB, Chen L, Rein SL, Engi SA, Quinlan V, Wilson L, Gilpin NW, Wills TA. Adolescent Alcohol Exposure Produces Sex-Specific Long-term Hyperalgesia via Changes in Central Amygdala Circuit Function. Biol Psychiatry 2024; 95:207-219. [PMID: 37717844 PMCID: PMC10866691 DOI: 10.1016/j.biopsych.2023.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/31/2023] [Accepted: 09/04/2023] [Indexed: 09/19/2023]
Abstract
BACKGROUND Exposure to alcohol during adolescence produces many effects that last well into adulthood. Acute alcohol use is analgesic, and people living with pain report drinking alcohol to reduce pain, but chronic alcohol use produces increases in pain sensitivity. METHODS We tested the acute and lasting effects of chronic adolescent intermittent ethanol (AIE) exposure on pain-related behavioral and brain changes in male and female rats. We also tested the long-term effects of AIE on synaptic transmission in midbrain (ventrolateral periaqueductal gray [vlPAG])-projecting central amygdala (CeA) neurons using whole-cell electrophysiology. Finally, we used circuit-based approaches (DREADDs [designer receptors exclusively activated by designer drugs]) to test the role of vlPAG-projecting CeA neurons in mediating AIE effects on pain-related outcomes. RESULTS AIE produced long-lasting hyperalgesia in male, but not female, rats. Similarly, AIE led to a reduction in synaptic strength of medial CeA cells that project to the vlPAG in male, but not female, rats. Challenge with an acute painful stimulus (i.e., formalin) in adulthood produced expected increases in pain reactivity, and this effect was exaggerated in male rats with a history of AIE. Finally, CeA-vlPAG circuit activation rescued AIE-induced hypersensitivity in male rats. CONCLUSIONS Our findings are the first, to our knowledge, to show long-lasting sex-dependent effects of adolescent alcohol exposure on pain-related behaviors and brain circuits in adult animals. This work has implications for understanding the long-term effects of underage alcohol drinking on pain-related behaviors in humans.
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Affiliation(s)
- Maria E Secci
- Department of Physiology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Leslie K Kelley
- Department of Physiology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Elizabeth M Avegno
- Department of Physiology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana; Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Eleanor B Holmgren
- Department of Anatomy and Cell Biology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Lily Chen
- Department of Anatomy and Cell Biology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Sydney L Rein
- Department of Anatomy and Cell Biology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Sheila A Engi
- Department of Anatomy and Cell Biology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Virginia Quinlan
- Department of Physiology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Lisa Wilson
- Department of Anatomy and Cell Biology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana
| | - Nicholas W Gilpin
- Department of Physiology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana; Neuroscience Center of Excellence, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana; Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana; Veterans Affairs Southeast Louisiana Healthcare System, New Orleans, Louisiana
| | - Tiffany A Wills
- Department of Anatomy and Cell Biology, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana; Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center School of Medicine, New Orleans, Louisiana.
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Akbar L, Castillo VCG, Olorocisimo JP, Ohta Y, Kawahara M, Takehara H, Haruta M, Tashiro H, Sasagawa K, Ohsawa M, Akay YM, Akay M, Ohta J. Multi-Region Microdialysis Imaging Platform Revealed Dorsal Raphe Nucleus Calcium Signaling and Serotonin Dynamics during Nociceptive Pain. Int J Mol Sci 2023; 24:ijms24076654. [PMID: 37047627 PMCID: PMC10094999 DOI: 10.3390/ijms24076654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 03/20/2023] [Accepted: 03/22/2023] [Indexed: 04/05/2023] Open
Abstract
In this research, we combined our ultralight micro-imaging device for calcium imaging with microdialysis to simultaneously visualize neural activity in the dorsal raphe nucleus (DRN) and measure serotonin release in the central nucleus of the amygdala (CeA) and the anterior cingulate cortex (ACC). Using this platform, we observed brain activity following nociception induced by formalin injection in the mouse’s hind paw. Our device showed that DRN fluorescence intensity increased after formalin injection, and the increase was highly correlated with the elevation in serotonin release in both the CeA and ACC. The increase in calcium fluorescence intensity occurred during the acute and inflammatory phases, which suggests the biphasic response of nociceptive pain. Furthermore, we found that the increase in fluorescence intensity was positively correlated with mouse licking behavior. Lastly, we compared the laterality of pain stimulation and found that DRN fluorescence activity was higher for contralateral stimulation. Microdialysis showed that CeA serotonin concentration increased only after contralateral stimulation, while ACC serotonin release responded bilaterally. In conclusion, our study not only revealed the inter-regional serotonergic connection among the DRN, the CeA, and the ACC, but also demonstrated that our device is feasible for multi-site implantation in conjunction with a microdialysis system, allowing the simultaneous multi-modal observation of different regions in the brain.
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Affiliation(s)
- Latiful Akbar
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Virgil Christian Garcia Castillo
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Joshua Philippe Olorocisimo
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Yasumi Ohta
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Mamiko Kawahara
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Hironari Takehara
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Makito Haruta
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Hiroyuki Tashiro
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
- Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka 819-0395, Japan
| | - Kiyotaka Sasagawa
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Masahiro Ohsawa
- Department of Neuropharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Yasemin M. Akay
- Biomedical Engineering Department, University of Houston, 3517 Cullen Blvd, Houston, TX 77204, USA
| | - Metin Akay
- Biomedical Engineering Department, University of Houston, 3517 Cullen Blvd, Houston, TX 77204, USA
| | - Jun Ohta
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
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Singh SP, Guindon J, Mody PH, Ashworth G, Kopel J, Chilakapati S, Adogwa O, Neugebauer V, Burton MD. Pain and aging: A unique challenge in neuroinflammation and behavior. Mol Pain 2023; 19:17448069231203090. [PMID: 37684099 PMCID: PMC10552461 DOI: 10.1177/17448069231203090] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 07/25/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Chronic pain is one of the most common, costly, and potentially debilitating health issues facing older adults, with attributable costs exceeding $600 billion annually. The prevalence of pain in humans increases with advancing age. Yet, the contributions of sex differences, age-related chronic inflammation, and changes in neuroplasticity to the overall experience of pain are less clear, given that opposing processes in aging interact. This review article examines and summarizes pre-clinical research and clinical data on chronic pain among older adults to identify knowledge gaps and provide the base for future research and clinical practice. We provide evidence to suggest that neurodegenerative conditions engender a loss of neural plasticity involved in pain response, whereas low-grade inflammation in aging increases CNS sensitization but decreases PNS sensitivity. Insights from preclinical studies are needed to answer mechanistic questions. However, the selection of appropriate aging models presents a challenge that has resulted in conflicting data regarding pain processing and behavioral outcomes that are difficult to translate to humans.
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Affiliation(s)
- Shishu Pal Singh
- Neuroimmunology and Behavior Laboratory, Department of Neuroscience, Center for Advanced Pain Studies (CAPS), School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Josee Guindon
- Garrison Institute on Aging and Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Prapti H Mody
- Neuroimmunology and Behavior Laboratory, Department of Neuroscience, Center for Advanced Pain Studies (CAPS), School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Gabriela Ashworth
- Garrison Institute on Aging and Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Jonathan Kopel
- Garrison Institute on Aging and Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Sai Chilakapati
- Neuroimmunology and Behavior Laboratory, Department of Neuroscience, Center for Advanced Pain Studies (CAPS), School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
- Department of Neurosurgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Owoicho Adogwa
- Department of Neurosurgery, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Volker Neugebauer
- Garrison Institute on Aging and Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Michael D Burton
- Neuroimmunology and Behavior Laboratory, Department of Neuroscience, Center for Advanced Pain Studies (CAPS), School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
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Tadros MA, Zouikr I, Hodgson DM, Callister RJ. Excitability of Rat Superficial Dorsal Horn Neurons Following a Neonatal Immune Challenge. Front Neurol 2018; 9:743. [PMID: 30245664 PMCID: PMC6137193 DOI: 10.3389/fneur.2018.00743] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/17/2018] [Indexed: 12/15/2022] Open
Abstract
Previous studies have shown that neonatal exposure to a mild inflammatory challenge, such as lipopolysaccharide (LPS, Salmonella enteriditis) results in altered pain behaviors later in life. To further characterize the impact of a neonatal immune challenge on pain processing, we examined the excitability of superficial dorsal horn (SDH) neurons following neonatal LPS exposure and subsequent responses to noxious stimulation at three time-points during early postnatal development. Wistar rats were injected with LPS (0.05 mg/kg i.p.) or saline on postnatal days (PNDs) 3 and 5, and later subjected to the formalin test at PNDs 7, 13, and 22. One hour after formalin injection into the plantar hindpaw, animals were euthanized (Ketamine, 100 mg/kg i.p.) and transverse slices from the lumbosacral spinal cord were prepared. Whole-cell patch-clamp recordings were made from SDH neurons (KCH3SO4-based internal, 22–24°C) on the ipsi- and contralateral sides of the spinal cord. Depolarising current steps were injected into SDH neurons to categorize action potential (AP) discharge. In both saline- and LPS-treated rats we observed age-related increases the percentage of neurons exhibiting tonic-firing, with concurrent decreases in single-spiking, between PND 7 and 22. In contrast, neonatal exposure to LPS failed to alter the proportions of AP discharge patterns at any age examined. We also assessed the subthreshold currents that determine AP discharge in SDH neurons. The rapid outward potassium current, IAr decreased in prevalence with age, but was susceptible to neonatal LPS exposure. Peak IAr current amplitude was greater in ipsilateral vs. contralateral SDH neurons from LPS-treated rats. Spontaneous excitatory synaptic currents (sEPSCs) were recorded to assess network excitability. Age-related increases were observed in sEPSC frequency and time course, but not peak amplitude, in both saline- and LPS-treated rats. Furthermore, sEPSC frequency was higher in ipsilateral vs. contralateral SDH neurons in LPS-treated animals. Taken together, these data suggest a neonatal immune challenge does not markedly affect the intrinsic properties of SDH neurons, however, it can increase the excitability of local spinal cord networks via altering the properties of rapid A-type currents and excitatory synaptic connections. These changes, made in neurons within spinal cord pain circuits, have the capacity to alter nociceptive signaling in the ascending pain pathway.
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Affiliation(s)
- Melissa A Tadros
- Faculty of Health and Hunter Medical Research Institute, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Ihssane Zouikr
- Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN, Wako, Saitama, Japan
| | - Deborah M Hodgson
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Callaghan, NSW, Australia
| | - Robert J Callister
- Faculty of Health and Hunter Medical Research Institute, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
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5
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Zouikr I, Karshikoff B. Lifetime Modulation of the Pain System via Neuroimmune and Neuroendocrine Interactions. Front Immunol 2017; 8:276. [PMID: 28348566 PMCID: PMC5347117 DOI: 10.3389/fimmu.2017.00276] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/24/2017] [Indexed: 12/12/2022] Open
Abstract
Chronic pain is a debilitating condition that still is challenging both clinicians and researchers. Despite intense research, it is still not clear why some individuals develop chronic pain while others do not or how to heal this disease. In this review, we argue for a multisystem approach to understand chronic pain. Pain is not only to be viewed simply as a result of aberrant neuronal activity but also as a result of adverse early-life experiences that impact an individual's endocrine, immune, and nervous systems and changes which in turn program the pain system. First, we give an overview of the ontogeny of the central nervous system, endocrine, and immune systems and their windows of vulnerability. Thereafter, we summarize human and animal findings from our laboratories and others that point to an important role of the endocrine and immune systems in modulating pain sensitivity. Taking "early-life history" into account, together with the past and current immunological and endocrine status of chronic pain patients, is a necessary step to understand chronic pain pathophysiology and assist clinicians in tailoring the best therapeutic approach.
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Affiliation(s)
- Ihssane Zouikr
- Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN BSI , Wako , Japan
| | - Bianka Karshikoff
- Department of Clinical Neuroscience, Division for Psychology, Karolinska Institutet, Solna, Sweden; Stress Research Institute, Stockholm University, Stockholm, Sweden
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6
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Campbell EJ, Watters SM, Zouikr I, Hodgson DM, Dayas CV. Recruitment of hypothalamic orexin neurons after formalin injections in adult male rats exposed to a neonatal immune challenge. Front Neurosci 2015; 9:65. [PMID: 25805965 PMCID: PMC4354278 DOI: 10.3389/fnins.2015.00065] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 02/16/2015] [Indexed: 11/26/2022] Open
Abstract
Exposure to early life physiological stressors, such as infection, is thought to contribute to the onset of psychopathology in adulthood. In animal models, injections of the bacterial immune challenge, lipopolysaccharide (LPS), during the neonatal period has been shown to alter both neuroendocrine function and behavioral pain responses in adulthood. Interestingly, recent evidence suggests a role for the lateral hypothalamic peptide orexin in stress and nociceptive processing. However, whether neonatal LPS exposure affects the reactivity of the orexin system to formalin-induced inflammatory pain in later life remains to be determined. Male Wistar rats (n = 13) were exposed to either LPS or saline (0.05 mg/kg, i.p) on postnatal days (PND) 3 and 5. On PND 80–97, all rats were exposed to a subcutaneous hindpaw injection of 2.25% formalin. Following behavioral testing, animals were perfused and brains processed for Fos-protein and orexin immunohistochemistry. Rats treated with LPS during the neonatal period exhibited decreased licking behaviors during the interphase of the formalin test, the period typically associated with the active inhibition of pain, and increased grooming responses to formalin in adulthood. Interestingly, these behavioral changes were accompanied by an increase in the percentage of Fos-positive orexin cells in the dorsomedial and perifornical hypothalamus in LPS-exposed animals. Similar increases in Fos-protein were also observed in stress and pain sensitive brain regions that receive orexinergic inputs. These findings highlight a potential role for orexin in the behavioral responses to pain and provide further evidence that early life stress can prime the circuitry responsible for these responses in adulthood.
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Affiliation(s)
- Erin J Campbell
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy and the Centre for Brain and Mental Health Research, Hunter Medical Research Institute, University of Newcastle Newcastle, NSW, Australia ; Laboratory of Neuroimmunology, School of Psychology, University of Newcastle Newcastle, NSW, Australia
| | - Stephanie M Watters
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy and the Centre for Brain and Mental Health Research, Hunter Medical Research Institute, University of Newcastle Newcastle, NSW, Australia ; Laboratory of Neuroimmunology, School of Psychology, University of Newcastle Newcastle, NSW, Australia
| | - Ihssane Zouikr
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle Newcastle, NSW, Australia
| | - Deborah M Hodgson
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle Newcastle, NSW, Australia
| | - Christopher V Dayas
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy and the Centre for Brain and Mental Health Research, Hunter Medical Research Institute, University of Newcastle Newcastle, NSW, Australia
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7
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Zouikr I, Ahmed AF, Horvat JC, Beagley KW, Clifton VL, Ray A, Thorne RF, Jarnicki AG, Hansbro PM, Hodgson DM. Programming of formalin-induced nociception by neonatal LPS exposure: Maintenance by peripheral and central neuroimmune activity. Brain Behav Immun 2015; 44:235-46. [PMID: 25449583 DOI: 10.1016/j.bbi.2014.10.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/10/2014] [Accepted: 10/23/2014] [Indexed: 12/22/2022] Open
Abstract
The immune and nociceptive systems are shaped during the neonatal period where they undergo fine-tuning and maturation. Painful experiences during this sensitive period of development are known to produce long-lasting effects on the immune and nociceptive responses. It is less clear, however, whether inflammatory pain responses are primed by neonatal exposure to mild immunological stimuli, such as with lipopolysaccharide (LPS). Here, we examine the impact of neonatal LPS exposure on inflammatory pain responses, peripheral and hippocampal interleukin-1β (IL-1β), as well as mast cell number and degranulation in preadolescent and adult rats. Wistar rats were injected with LPS (0.05mg/kg IP, Salmonella enteritidis) or saline on postnatal days (PNDs) 3 and 5 and later subjected to the formalin test at PNDs 22 and 80-97. At both time-points, and one-hour after formalin injection, blood and hippocampus were collected for measuring circulating and central IL-1β levels using ELISA and Western blot, respectively. Paw tissue was also isolated to assess mast cell number and degree of degranulation using Toluidine Blue staining. Behavioural analyses indicate that at PND 22, LPS-challenged rats displayed enhanced flinching (p<.01) and licking (p<.01) in response to formalin injection. At PNDs 80-97, LPS-challenged rats exhibited increased flinching (p<.05), an effect observed in males only. Furthermore, neonatal LPS exposure enhanced circulating IL-1β and mast cell degranulation in preadolescent but not adult rats following formalin injection. Hippocampal IL-1β levels were increased in LPS-treated adult but not preadolescent rats in response to formalin injection. These data suggest neonatal LPS exposure produces developmentally regulated changes in formalin-induced behavioural responses, peripheral and central IL-1β levels, as well as mast cell degranulation following noxious stimulation later in life. These findings highlight the importance of immune activation during the neonatal period in shaping immune response and pain sensitivity later in life. This is of clinical relevance given the high prevalence of bacterial infection during the neonatal period, particularly in the vulnerable population of preterm infants admitted to neonatal intensive care units.
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Affiliation(s)
- Ihssane Zouikr
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia; School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia; Hunter Medical Research Institute, Newcastle, New South Wales, Australia.
| | - Abdulrzag F Ahmed
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Jay C Horvat
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia; Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Kenneth W Beagley
- Institute of Health Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Vicki L Clifton
- Robinson Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Allyson Ray
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
| | - Rick F Thorne
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia; Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Andrew G Jarnicki
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Philip M Hansbro
- Hunter Medical Research Institute, Newcastle, New South Wales, Australia
| | - Deborah M Hodgson
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
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Zouikr I, James MH, Campbell EJ, Clifton VL, Beagley KW, Dayas CV, Hodgson DM. Altered formalin-induced pain and Fos induction in the periaqueductal grey of preadolescent rats following neonatal LPS exposure. PLoS One 2014; 9:e98382. [PMID: 24878577 PMCID: PMC4039471 DOI: 10.1371/journal.pone.0098382] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/02/2014] [Indexed: 11/18/2022] Open
Abstract
Animal and human studies have demonstrated that early pain experiences can produce alterations in the nociceptive systems later in life including increased sensitivity to mechanical, thermal, and chemical stimuli. However, less is known about the impact of neonatal immune challenge on future responses to noxious stimuli and the reactivity of neural substrates involved in analgesia. Here we demonstrate that rats exposed to Lipopolysaccharide (LPS; 0.05 mg/kg IP, Salmonella enteritidis) during postnatal day (PND) 3 and 5 displayed enhanced formalin-induced flinching but not licking following formalin injection at PND 22. This LPS-induced hyperalgesia was accompanied by distinct recruitment of supra-spinal regions involved in analgesia as indicated by significantly attenuated Fos-protein induction in the rostral dorsal periaqueductal grey (DPAG) as well as rostral and caudal axes of the ventrolateral PAG (VLPAG). Formalin injections were associated with increased Fos-protein labelling in lateral habenula (LHb) as compared to medial habenula (MHb), however the intensity of this labelling did not differ as a result of neonatal immune challenge. These data highlight the importance of neonatal immune priming in programming inflammatory pain sensitivity later in development and highlight the PAG as a possible mediator of this process.
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Affiliation(s)
- Ihssane Zouikr
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
- * E-mail:
| | - Morgan H. James
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Erin J. Campbell
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Vicki L. Clifton
- Robinson Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Kenneth W. Beagley
- Institute of Health Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Christopher V. Dayas
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Deborah M. Hodgson
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
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10
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Zouikr I, Tadros MA, Barouei J, Beagley KW, Clifton VL, Callister RJ, Hodgson DM. Altered nociceptive, endocrine, and dorsal horn neuron responses in rats following a neonatal immune challenge. Psychoneuroendocrinology 2014; 41:1-12. [PMID: 24495603 DOI: 10.1016/j.psyneuen.2013.11.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 01/16/2023]
Abstract
The neonatal period is characterized by significant plasticity where the immune, endocrine, and nociceptive systems undergo fine-tuning and maturation. Painful experiences during this period can result in long-term alterations in the neurocircuitry underlying nociception, including increased sensitivity to mechanical or thermal stimuli. Less is known about the impact of neonatal exposure to mild inflammatory stimuli, such as lipopolysaccharide (LPS), on subsequent inflammatory pain responses. Here we examine the impact of neonatal LPS exposure on inflammatory pain sensitivity and HPA axis activity during the first three postnatal weeks. Wistar rats were injected with LPS (0.05mg/kg IP, Salmonella enteritidis) or saline on postnatal days (PNDs) 3 and 5 and later subjected to the formalin test at PNDs 7, 13, and 22. One hour after formalin injection, blood was collected to assess corticosterone responses. Transverse spinal cord slices were also prepared for whole-cell patch clamp recording from lumbar superficial dorsal horn neurons (SDH). Brains were obtained at PND 22 and the hypothalamus was isolated to measure glucocorticoid (GR) and mineralocorticoid receptor (MR) transcript expression using qRT-PCR. Behavioural analyses indicate that at PND 7, no significant differences were observed between saline- or LPS-challenged rats. At PND 13, LPS-challenged rats exhibited enhanced licking (p<.01), and at PND 22, increased flinching in response to formalin injection (p<.05). LPS-challenged rats also displayed increased plasma corticosterone at PND 7 and PND 22 (p<.001) but not at PND 13 following formalin administration. Furthermore, at PND 22 neonatal LPS exposure induced decreased levels of GR mRNA and increased levels of MR mRNA in the hypothalamus. The intrinsic properties of SDH neurons were similar at PND 7 and PND 13. However, at PND 22, ipsilateral SDH neurons in LPS-challenged rats had a lower input resistance compared to their saline-challenged counterparts (p<.05). These data suggest neonatal LPS exposure produces developmentally regulated changes in formalin-induced behavioural responses, corticosterone levels, and dorsal horn neuron properties following noxious stimulation later in life. These findings highlight the importance of immune activation during the neonatal period in shaping pain sensitivity later in life. This programming involves both spinal cord neurons and the HPA axis.
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Affiliation(s)
- Ihssane Zouikr
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
| | - Melissa A Tadros
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Javad Barouei
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia
| | - Kenneth W Beagley
- Institute of Health Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Vicki L Clifton
- Robinson Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Robert J Callister
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Deborah M Hodgson
- Laboratory of Neuroimmunology, School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia.
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Inflammatory pain and corticosterone response in infant rats: effect of 5-HT1A agonist buspirone prior to gestational stress. Mediators Inflamm 2013; 2013:915189. [PMID: 23606797 PMCID: PMC3628187 DOI: 10.1155/2013/915189] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/06/2013] [Indexed: 01/18/2023] Open
Abstract
Our researches have shown that gestational stress causes exacerbation of inflammatory pain in the offspring; the maternal 5-HT1A agonist buspirone before the stress prevents the adverse effect. The serotonergic system and hypothalamo-pituitary-adrenal (HPA) axis are closely interrelated. However, interrelations between inflammatory pain and the HPA axis during the hyporeactive period of the latter have not been studied. The present research demonstrates that formalin-induced pain causes a gradual and prolonged increase in plasma corticosterone level in 7-day-old male rats; twenty-four hours after injection of formalin, the basal corticosterone level still exceeds the initial basal corticosterone value. Chronic treatments of rat dams with buspirone before restraint stress during gestation normalize in the offspring pain-like behavior and induce during the acute phase in the formalin test the stronger corticosterone increase as compared to the stress hormonal elevation in animals with other prenatal treatments. Negative correlation between plasma corticosterone level and the number of flexes+shakes is revealed in buspirone+stress rats. The new data enhance the idea about relativity of the HPA axis hyporeactive period and suggest that maternal buspirone prior to stress during gestation may enhance an adaptive mechanism of the inflammatory nociceptive system in the infant male offspring through activation of the HPA axis peripheral link.
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